A burial team in Liberia awaits decontamination after performing "safe burials" for people who died of Ebola during the 2014-15 outbreak. Strains of the virus are harbored by bats and primates. A new study looks at how human activity affects the transmission of infectious diseases like Ebola. John Moore/Getty Images hide caption

This building in Rafah, in southern Gaza, was destroyed by Israeli bombardment in December. amid continuing battles between Israel and Hamas. Mahmud Hams/AFP via Getty Images hide caption

The new documentary Agent of Happiness follows Bhutanese bureaucrats who survey people about their state of mind. From left: director Dorottya Zurbó, happiness agents Amber Kumar Gurung and Guna Raj Kuikel, and director Arun Bhattarai. DDA hide caption

Pakistani women jostle to receive their ballot papers prior to casting their ballot at a polling station on May 11, 2013 in Lahore. A study in The Lancet provides evidence that free and fair elections are associated with a lower burden of chronic diseases. Daniel Berehulak/Getty Images hide caption

Researchers studied the gut microbes of runners from the Boston Marathon, isolating one strain of bacteria that may boost athletic performance. Nicolaus Czarnecki/Boston Herald via Getty Images hide caption

In Nigeria's oil-rich Niger Delta, oil bunkering — the practice of siphoning oil from pipelines — has transformed parts of the once-thriving delta ecosystem into an ecological dead zone, according to the U.N. Environment Programme. Edward Burtynsky, courtesy Robert Koch Gallery, San Francisco / Nicholas Metivier Gallery, Toronto hide caption

Fecal transplantation is an experimental procedure to treat intestinal conditions, including recurrent, antibiotic-resistant Clostridium difficile infection. But if the donor stool is not properly screened, it can spread other illnesses. SCIENCE PHOTO LIBRARY/Science Source hide caption

An FDA inspection of this Ranbaxy facility in Toansa, Punjab, India, in 2014, revealed drug quality testing violations, resulting in the FDA prohibiting Ranbaxy from marketing drugs in the U.S. that were manufactured at this plant. Dhiraj Singh/Getty Images hide caption

Measles vaccination rates need to be at 93% to 95% to keep herd immunity. Otherwise, very young infants or other vulnerable people can be exposed to the virus. George Frey/Getty Images hide caption

Measles used to be a common childhood disease, but after an effective vaccine was developed, the disease was declared eliminated in the U.S. in 2000. This year's outbreaks, however, put that status in jeopardy. solidcolours/Getty Images hide caption

While it may seem that heaps of plastic from meal kit delivery services like Blue Apron make them less environmentally friendly than traditional grocery shopping, a new study says the kits actually produce less food waste. Derek Davis/Portland Press Herald via Getty Images hide caption

Rain wands would have been planted in the earth to bring seasonal rains. Olivia Sun for NPR hide caption

Fisher-Price has recalled its popular Rock 'n Play sleeper, after the Consumer Product Safety Commission confirmed that least 30 babies' deaths were linked to it. Courtesy of US Consumer Product Safety Commission hide caption

tk Courtesy of Rob Reinhart hide caption

An aerial view of a combine harvesting corn in a field near Jarrettsville, Md. A new study ties an estimated 4,300 premature deaths a year to the air pollution caused by corn production in the U.S. Edwin Remsberg/Getty Images hide caption

Researchers tested sewage across Europe, including in Germany, where this treatment plant is located, for bacteria with resistance to antibiotics. B&M Noskowski/Getty Images hide caption